JP2604391B2 - Display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a display device, and more particularly, to a display device suitable for application to a device capable of displaying a plurality of video signals having different numbers of horizontal scanning lines.

[Prior Art] In the recent internationalization situation, there are many people who travel abroad for business or other purposes, and portable liquid crystal television receivers also use a plurality of types of television signals for such people. Some of them have been proposed. For example, NTSC television signals used in North America and Japan, and PA signals mainly used in Europe
2. Description of the Related Art A liquid crystal television receiver capable of receiving both L-type television signals has been proposed.

[Problems to be Solved by the Invention] By the way, in a conventional liquid crystal television receiver supporting a plurality of systems, the number of pixels in the vertical direction of the liquid crystal display panel is determined in accordance with the number of horizontal scanning lines of one of the systems. I was

However, if the number of pixels in the vertical direction is matched to the PAL system with a large number of horizontal scanning lines, the lower part of the display screen in the vertical direction will not be displayed when receiving an NTSC television signal with a small number of horizontal scanning lines. Becomes
The displayed image was difficult to see.

Conversely, when the number of pixels in the vertical direction of the liquid crystal display panel is adjusted to the number of horizontal scanning lines in the NTSC system, many parts below the received image are missing when receiving the television signal in the PAL system, and the received image is not displayed. Only a part was displayed.

The present invention has been made in view of the above points, and aims to provide a display device that can display the entire display panel without any excess or shortage even when video signals having different numbers of horizontal scanning lines arrive. Is what you do.

[Means for Solving the Problems] In order to solve such problems, the display device of the present invention includes:
A display panel in which images are arranged vertically and horizontally, wherein the number of pixels in the vertical direction is selected to be approximately a common multiple of the number of horizontal scanning lines to be displayed for a plurality of video signals having different numbers of horizontal scanning lines; A horizontal drive circuit for selecting pixels in the horizontal direction of the display panel; and a plurality of horizontal scan lines to be displayed for each horizontal scan line of the video signal selected from the plurality of video signal columns. A vertical drive circuit for simultaneously selecting pixels in the vertical direction row by row.

[Operation] The number of pixels in the vertical direction of the display panel is selected to be approximately a common multiple of the number of horizontal scanning lines to be displayed for video signals having different numbers of horizontal scanning lines, and is set to the number of horizontal scanning lines to be displayed of the selected video signal. In addition, video signals are displayed by simultaneously selecting pixels in the vertical direction for one horizontal scanning line for each of a plurality of rows.

As a result, regardless of which video signal is selected, the received image can be displayed over the entire display screen without excess or deficiency.

Embodiment Hereinafter, an embodiment in which the present invention is applied to a liquid crystal monochrome television receiver compatible with the NTSC system / PAL system will be described in detail with reference to the drawings.

FIG. 1 shows a pixel arrangement of a liquid crystal display panel 1 of this embodiment. In a display area having an aspect ratio of 3: 4, the number of pixels in the horizontal direction is the same as the conventional one, and the number of pixels in the vertical direction is 1440. Of pixels are arranged.

In the horizontal direction of the liquid crystal display panel 1, pixels are sequentially selected in synchronization with the horizontal direction by a horizontal drive circuit (not shown) in the same manner as in the conventional device. about,
Pixels are selected by the vertical drive circuit 2 shown in FIG.

The vertical drive circuit 2 includes a 240-stage first shift register 3 for the NTSC system and a 288-stage second shift register 4 for the PAL system. The NTSC system is operated in response to the system command signal MD from the control circuit 5. The first shift register 3
Is selected, while the second shift register 4 is selected in the PAL system.

When the first and second shift registers 3 and 4 both receive the vertical drive signal VD from the control circuit 5,
The output of the first stage is made significant regardless of the odd field and the even field, and thereafter, the output of the next stage is made significant each time the horizontal drive signal HD is supplied from the control circuit 5.

Outputs of the first stage of the first shift register 3 are sent through the first buffer amplifier circuit A1 and further through the respective backflow preventing diodes D1 to D6 to the first row to the first row of the liquid crystal display panel 1 described above. It is provided to the gate lines L1 to L6 for the pixels in the sixth row. The output of the second stage of the shift register 3 is sent to the seventh to twelfth rows of the liquid crystal display panel 1 through the second buffer amplifier circuit A2 and further through the diodes D7 to D12 for preventing backflow. Are applied to the gate lines L7 to L12 for the pixels of. Hereinafter, similarly, the N-th shift register 3 (N = 1 to 24)
0) The output of the stage is further passed through the N-th buffer amplifier circuit AN, and further to each of the backflow preventing diodes D (6N-5) to D (6N-5) to D
(6N) to the gate lines L (6N-5) to L (6N) for the pixels in the 6N-5th row to the 6Nth row of the liquid crystal display panel 1.

On the other hand, the output of the first stage of the second shift register 4 is
Through the first buffer amplifier circuit a1, and further through the backflow preventing diodes d1 to d5, the first of the liquid crystal display panel 1
It is provided to the gate lines L1 to L5 for the pixels of the rows to the fifth row. Further, the output of the second stage of the shift register 4 is passed through the second buffer amplifier circuit a2,
Further, it is provided to the gate lines L6 to L10 for the pixels in the sixth to tenth rows of the liquid crystal display panel 1 via the backflow preventing diodes d6 to d10. Less than,
Similarly, the M-th shift register 3 (M = 1 to 288)
The output of the stage is further passed through the M-th buffer amplifier circuit aM and further to each of the backflow preventing diodes d ((5M−4) to d (5M−5).
M) to the gate lines L (5M-4) to L (5M) for the pixels in the 5M-4th row to the 5Mth row of the liquid crystal display panel 1.

For the display device having the above configuration, when the NTSC system is selected by an operation switch (not shown), or when the NTSC system is selected by a system automatic discrimination circuit (not shown),
After the control circuit 5 selects the first shift register 3 and selects the first stage in synchronization with the vertical drive signal VD,
The output stage of the shift register 3 is sequentially changed in synchronization with the horizontal drive signal HD.

As a result, the liquid crystal display panel 1 causes the pixels in the first to sixth rows to be simultaneously selected for the first horizontal operation line of the incoming television signal. To select the pixels in the 6N-5th row to the 6Nth row at the same time. Therefore, a television signal of 240 horizontal scanning lines is displayed for each pixel in every six rows in the vertical direction in both the odd field and the even field, and the received image is displayed on the entire display screen having the aspect ratio of 3: 4.

On the other hand, when the PAL system is selected, the control circuit 5
Selects the second shift register 4, selects the first stage in synchronization with the vertical drive signal VD, and then sequentially changes the output stage of the shift register 4 in synchronization with the horizontal drive signal HD.

As a result, the liquid crystal display panel 1 causes the pixels in the first to fifth rows to be simultaneously selected with respect to the first horizontal scanning line of the arriving television signal. 5M-4th to 5Mth rows are selected at the same time. Therefore, a television signal of 288 horizontal scanning lines is displayed for each pixel of every six rows in the vertical direction in both the odd field and the even field, and the received image is displayed on the entire display screen having the aspect ratio of 3: 4.

Therefore, according to the above-described embodiment, the number of pixels in the vertical direction of the liquid crystal display panel 1 is selected to be a common integral multiple (common multiple) of the number of horizontal scanning lines to be displayed in each system, and a plurality of rows corresponding to the system are selected. Are driven simultaneously in synchronization with each horizontal scanning line, so that a received image can be displayed on the entire display screen with almost no shortage when receiving any type of television signal.

In the above-described embodiment, the liquid crystal television receiver applied to the NTSC / PAL system has been described. However, the combination of the systems is not limited to this, and furthermore, a predetermined combination from a personal computer or the like may be used. May be applied to those displaying a video signal having the number of horizontal scanning lines. Further, the present invention may be applied to not only a liquid crystal display device but also a plasma display or an EL display device in which pixels are arranged vertically and horizontally.

In the above embodiment, the number of pixels in the vertical direction is
Although the case where the number is set to 1440 is shown, it may be appropriately selected according to the number of horizontal scanning lines to be displayed. For example, even in the case of the same NTSC / PAL system as in the above-described embodiment, the video signal of 250 horizontal scanning lines is displayed in the case of the NTSC system by selecting 1500, and 300 lines in the case of the PAL system. A video signal of a horizontal scanning line may be displayed.

Further, the configuration of the vertical drive circuit 2 for sequentially selecting and driving five or six gate lines is not limited to that of the above-described embodiment.

Further, in the above-described embodiment, the same five fields or six fields are selected in the odd field and the even field.
A pseudo interlace may be realized by selecting five or six gate lines shifted by up to three lines.

[Effects of the Invention] As described above, according to the present invention, the number of pixels in the vertical direction of the display panel is selected to be approximately a common multiple of the number of horizontal scanning lines to be displayed for video signals having different numbers of horizontal scanning lines. A plurality of rows of pixels corresponding to the number of horizontal scanning lines to be displayed for the horizontal scanning lines are simultaneously selected and displayed in the vertical direction, so that any video signal is displayed on the entire display screen. It is possible to obtain a display device that can display the received image without any excess or shortage.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a pixel arrangement of an embodiment of a display device according to the present invention, and FIG. 2 is a block diagram showing a vertical drive circuit thereof. 1 ... LCD panel, 2 ... vertical drive circuit, 3,
4 shift register, 5 control circuit, L1 to
L1440: Gate line for pixels of the liquid crystal display panel.

Claims (1)

(57) [Claims] 1. A display panel in which images are arranged vertically and horizontally, wherein the number of pixels in the vertical direction is selected to be approximately a common multiple of the number of horizontal scanning lines to be displayed for a plurality of video signals having different numbers of horizontal scanning lines. A display panel, a horizontal drive circuit for selecting pixels in the horizontal direction of the display panel, and the number of horizontal scan lines to be displayed for each horizontal scan line of a video signal selected from the plurality of video signals. A vertical drive circuit for simultaneously selecting a plurality of rows of pixels in the vertical direction at the same time.